﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    class yuan:xingzhuang
    {
        double  r;
        public double   R
        {
            get { return this.r; }
            set { this.r = value; }
        }
        public virtual void GetArea(double a)
        {
            double  s = 3.14 * (a * a);
            Console.WriteLine(s);
        }
    }
}
